JP7150437B2 - Manufacturing method of multilayer ceramic capacitor - Google Patents

Description

The present invention relates to a multilayer ceramic capacitor having side margins.

2. Description of the Related Art In recent years, with the miniaturization and high performance of electronic equipment, there has been an increasing demand for miniaturization and large-capacity multilayer ceramic capacitors used in electronic equipment. To meet this demand, it is effective to enlarge the internal electrodes of the laminated ceramic capacitor. In order to enlarge the internal electrodes, it is necessary to thin the side margin portions for ensuring insulation around the internal electrodes.

On the other hand, in a general method of manufacturing a multilayer ceramic capacitor, it is difficult to form side margin portions with a uniform thickness due to the accuracy of each step (for example, patterning of internal electrodes, cutting of laminated sheets, etc.). Therefore, in such a method of manufacturing a multilayer ceramic capacitor, the thinner the side margins, the more difficult it becomes to ensure insulation around the internal electrodes.

Patent Literature 1 discloses a technique for retrofitting a side margin portion. In other words, in this technique, in the green chip with the internal electrodes exposed on the side surfaces, the side surfaces of the green chip are pressed against the ceramic green sheets. As a result, ceramic protective layers (side margin portions) are provided by punching out the side ceramic green sheets. Since this technique makes it possible to form a side margin portion with a uniform thickness, it is possible to ensure insulation around the internal electrodes even when the side margin portion is made thin.

JP 2012-209539 A

On the other hand, as described in Patent Document 1, when the side surface of the green chip is pressed against the ceramic green sheet for the side surface, the ceramic green sheet may turn over and stick to surfaces other than the side surface of the green chip. On the other hand, the ceramic green sheet was not sufficiently punched out, and the side margin portions could not be formed in some cases.

SUMMARY OF THE INVENTION In view of the circumstances as described above, an object of the present invention is to provide a multilayer ceramic capacitor having side margin portions of an appropriate shape.

To achieve the above object, a multilayer ceramic capacitor according to one aspect of the present invention includes a multilayer portion and side margin portions.
The lamination section has a capacitance forming section, a lead-out section, and a cover section.
In the capacitance forming portion, internal electrodes are stacked in the first direction.
The extraction portion extends from the capacitance forming portion in a second direction perpendicular to the first direction, and the internal electrode is extracted.
The cover portion covers the capacitance forming portion and the lead portion from the first direction.
The laminated portion has a main surface facing in the first direction, an end surface facing in the second direction, and side surfaces facing in a third direction orthogonal to the first direction and the second direction.
The side margin portion is provided on the side surface.
The above aspect
A first straight portion extending in the second direction and configured by the outer edge of the main surface, a second straight portion extending in the first direction and configured by the outer edge of the end face, the first straight portion and the second straight portion. and a corner portion connecting the straight portions,
The corners are
the distance along the first direction between the first imaginary line along which the first straight portion extends in the second direction and the end point of the second straight portion on the first imaginary line side; a second imaginary line extending in the first direction from the second linear portion; and an end portion of the lead portion exposed from the side surface and positioned at a boundary between the capacitance forming portion and the cover portion. and b is the distance along the second direction, the curve satisfies the conditions of 0.4≦a/b≦2.5 and 10 μm≦a and b≦60 μm.

With the above configuration, the side surfaces of the laminated portion where the side margin portions are formed are configured in a rectangular shape with rounded corners. When the side margin portions are formed by punching out the ceramic sheet for forming the side margin portions, the corner portions that satisfy the above conditions can disperse the load on the ceramic sheet and apply shear force of an appropriate magnitude. As a result, the ceramic sheet can be punched out in a shape along the outer edge of the side surface, and a side margin portion having an appropriate shape can be provided.

The corner may be curved so as to satisfy the condition 0.5≦a/b≦1.5.
As a result, it is possible to effectively suppress the concentration of the shearing force in the vicinity of the corners of the ceramic sheet, and to more reliably prevent appearance defects in the side margin portions.

The corners may be curved to satisfy the conditions of 1.0≦a/b≦1.5 and 10 μm≦b≦30 μm.
As a result, even when the length dimension along the second direction of the lead-out portion is shortened, a shearing force of an appropriate magnitude can be applied to the ceramic sheet. Therefore, it is possible to increase the proportion of the capacitance forming portion in the multilayer ceramic capacitor, realize a small size and increase the capacitance, and provide a side margin portion having an appropriate shape.

As described above, according to the present invention, it is possible to provide a multilayer ceramic capacitor capable of providing side margin portions having an appropriate shape.

1 is a perspective view of a laminated ceramic capacitor according to one embodiment of the present invention; FIG. FIG. 2 is a cross-sectional view of the multilayer ceramic capacitor taken along line AA' in FIG. 1; 2 is a cross-sectional view of the multilayer ceramic capacitor taken along line BB' of FIG. 1; FIG. 4 is a flow chart showing a method for manufacturing the laminated ceramic capacitor. It is a top view which shows the manufacturing process of the said laminated ceramic capacitor. It is a perspective view which shows the manufacturing process of the said laminated ceramic capacitor. It is a cross-sectional view showing a manufacturing process of the laminated ceramic capacitor. It is a perspective view which shows the manufacturing process of the said laminated ceramic capacitor. It is a cross-sectional view showing a manufacturing process of the laminated ceramic capacitor. It is a cross-sectional view showing a manufacturing process of the laminated ceramic capacitor. It is a cross-sectional view showing a manufacturing process of the laminated ceramic capacitor. It is a perspective view which shows the manufacturing process of the said laminated ceramic capacitor. FIG. 3 is a partially enlarged view of FIG. 2; FIG. 4 is a perspective view showing an unfired laminated chip according to a comparative example of the present embodiment; It is a top view which shows the manufacturing process of the laminated ceramic capacitor based on the said comparative example. It is a sectional view showing a manufacturing process of a monolithic ceramic capacitor concerning the above-mentioned comparative example. FIG. 4 is a perspective view showing an unfired ceramic body according to the comparative example;

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The drawings show mutually orthogonal X, Y and Z axes where appropriate. The X-axis, Y-axis, and Z-axis are common in all drawings.

[Overall Configuration of Multilayer Ceramic Capacitor 10]
1 to 3 are diagrams showing a multilayer ceramic capacitor 10 according to one embodiment of the present invention. FIG. 1 is a perspective view of a laminated ceramic capacitor 10. FIG. FIG. 2 is a cross-sectional view of the multilayer ceramic capacitor 10 taken along line AA' in FIG. FIG. 3 is a cross-sectional view of the multilayer ceramic capacitor 10 taken along line BB' of FIG.

A laminated ceramic capacitor 10 includes a ceramic element body 11 , a first external electrode 14 and a second external electrode 15 . The ceramic body 11 typically has two main surfaces oriented in the Z-axis direction, two end surfaces oriented in the X-axis direction, and two side surfaces oriented in the Y-axis direction. The ridges connecting the surfaces of the ceramic body 11 are rounded.

The external electrodes 14 and 15 cover the end faces of the ceramic body 11 and face each other in the X-axis direction with the ceramic body 11 interposed therebetween. The external electrodes 14 and 15 extend from the end surfaces of the ceramic body 11 to the main surface and side surfaces. As a result, the external electrodes 14 and 15 have a U-shaped cross section parallel to the XZ plane and a cross section parallel to the XY plane. The shape of the external electrodes 14 and 15 is not limited to that shown in FIG.

The external electrodes 14 and 15 are made of a good electrical conductor. Good electrical conductors forming the external electrodes 14 and 15 include, for example, copper (Cu), nickel (Ni), tin (Sn), palladium (Pd), platinum (Pt), silver (Ag), and gold (Au). and the like as a main component.

The ceramic body 11 is made of dielectric ceramics and has a laminated portion 16 and side margin portions 17 . The laminated portion 16 is formed with two end surfaces 16a facing in the X-axis direction, two side surfaces 16b facing in the Y-axis direction, and two main surfaces 16c facing in the Z-axis direction. The side margin portion 17 covers two side surfaces 16b of the laminated portion 16, respectively.
Note that the cross section shown in FIG. 2 corresponds to the side surface 16 b of the laminated portion 16 .

The laminated portion 16 has a configuration in which a plurality of flat ceramic layers extending along the XY plane are laminated in the Z-axis direction. The laminated portion 16 has a capacitance forming portion 18 , two lead portions 19 , and two cover portions 20 . The lead portions 19 are provided on both sides of the capacitance forming portion 18 in the X-axis direction. The lead portion 19 constitutes an end surface 16 a connected to the external electrodes 14 and 15 together with the cover portion 20 .

The cover portion 20 covers the capacitance forming portion 18 and the lead portion 19 from above and below in the Z-axis direction. The surface of the cover portion 20 facing in the Z-axis direction constitutes two main surfaces 16 c of the laminated portion 16 . The cover portion 20 includes a first cover region 21 that covers the upper and lower sides of the capacity forming portion 18 in the Z-axis direction, and a second cover region 22 that covers the upper and lower sides of the lead portion 19 in the Z-axis direction. A flat region 16d is formed on the main surface 16c on the first cover region 21 (see FIG. 13).

The capacitance forming portion 18 has a plurality of sheet-like first internal electrodes 12 and second internal electrodes 13 extending along the XY plane. In the capacitance forming portion 18, the internal electrodes 12 and 13 are alternately stacked in the Z-axis direction with a plurality of ceramic layers interposed therebetween. That is, the internal electrodes 12 and 13 face each other in the Z-axis direction with the ceramic layer interposed therebetween. The capacitance forming portion 18 has a function of storing charges in the multilayer ceramic capacitor 10 .

The internal electrodes 12 and 13 are formed over the entire width of the capacitance forming portion 18 in the Y-axis direction and are exposed on both side surfaces 16 b of the laminated portion 16 . In the ceramic body 11 , insulation between adjacent internal electrodes 12 and 13 on both side surfaces 16 b of the laminated portion 16 is ensured by the side margin portions 17 covering the side surfaces 16 b of the laminated portion 16 .

In the first lead portion 19 a of the lead portion 19 , the first internal electrode 12 extends outward in the X-axis direction from the capacitance forming portion 18 to the end face 16 a in contact with the first external electrode 14 . In the second lead-out portion 19b, the second internal electrode 13 extends outward in the X-axis direction from the capacitance forming portion 18 to the end face 16a in contact with the second external electrode 15. As shown in FIG. Thereby, the first internal electrode 12 is connected to the first external electrode 14 and the second internal electrode 13 is connected to the second external electrode 15 .

The ceramic layer between the first internal electrodes 12 of the first lead-out portion 19 a functions as an end margin that ensures insulation between the second internal electrode 13 and the first external electrode 14 . Similarly, the ceramic layer between the second internal electrodes 13 of the second lead-out portion 19b functions as an end margin that ensures insulation between the first internal electrode 12 and the second external electrode 15. As shown in FIG.

With such a configuration, in the multilayer ceramic capacitor 10, when a voltage is applied between the first external electrode 14 and the second external electrode 15, the plurality of voltages between the first internal electrode 12 and the second internal electrode 13 A voltage is applied to the ceramic layer of As a result, in the multilayer ceramic capacitor 10 , electric charges corresponding to the voltage between the first external electrode 14 and the second external electrode 15 are stored.

In the ceramic body 11, dielectric ceramics with a high dielectric constant are used in order to increase the capacitance of each ceramic layer between the internal electrodes 12,13. Dielectric ceramics with a high dielectric constant include, for example, perovskite structure materials containing barium (Ba) and titanium (Ti), represented by barium titanate (BaTiO ₃ ).

Note that the ceramic layer includes strontium titanate (SrTiO ₃ ), calcium titanate (CaTiO ₃ ), magnesium titanate (MgTiO ₃ ), calcium zirconate (CaZrO ₃ ), calcium zirconate titanate (Ca( Zr, Ti)O ₃ ) system, barium zirconate (BaZrO ₃ ) system, titanium oxide (TiO ₂ ) system, or the like may be used.

The internal electrodes 12 and 13 are made of a good electrical conductor. Nickel (Ni) is typically used as a good electrical conductor forming the internal electrodes 12 and 13. In addition, copper (Cu), palladium (Pd), platinum (Pt), silver (Ag), A metal or alloy containing gold (Au) or the like as a main component can be used.

The configuration of the laminated ceramic capacitor 10 according to this embodiment is not limited to the configurations shown in FIGS. For example, the number of internal electrodes 12 and 13 can be appropriately determined according to the size and performance required of the multilayer ceramic capacitor 10 .

As shown in FIG. 2, the main surface 16c on the second cover area 22 curves inward in the Z-axis direction. Along with this, the lead portion 19 is also configured such that the height dimension in the Z-axis direction gradually decreases from the capacitance forming portion 18 toward the end face 16a, and the internal electrodes 12 and 13 of the lead portion 19 also extend toward the end face 16a. It is arranged so as to curve inward in the Z-axis direction. For example, the height dimension along the Z-axis direction of the lead portion 19 at the end face 16 a is 80% or less of the height dimension along the Z-axis direction of the lead portion 19 at the boundary portion with the capacitance forming portion 18 .

Thereby, the side surface 16b is configured in a rectangular shape with rounded corners.
The laminated ceramic capacitor 10 having the above configuration is formed by the following manufacturing method.

[Manufacturing Method of Multilayer Ceramic Capacitor 10]
FIG. 4 is a flow chart showing the manufacturing method of the multilayer ceramic capacitor 10. As shown in FIG. 5 to 12 are diagrams schematically showing the manufacturing process of the multilayer ceramic capacitor 10. FIG. Hereinafter, a method for manufacturing the laminated ceramic capacitor 10 will be described along FIG. 4 with reference to FIGS. 5 to 12 as appropriate.

(Step S01: Ceramic sheet lamination)
In step S01, a first ceramic sheet 101 and a second ceramic sheet 102 for forming the capacitance forming portion 18 and a third ceramic sheet 103 for forming the cover portion 20 are prepared and laminated.

The ceramic sheets 101, 102, 103 are configured as unfired dielectric green sheets containing dielectric ceramics as a main component. The ceramic sheets 101, 102, 103 are formed into sheets using, for example, a roll coater or a doctor blade. The thickness of the ceramic sheets 101, 102, 103 can be adjusted appropriately.

FIG. 5 is a plan view of the ceramic sheets 101, 102, 103. FIG. At this stage, the ceramic sheets 101, 102, 103 are constructed as large sheets that are not singulated. FIG. 5 shows cutting lines Lx and Ly used when individualizing each laminated ceramic capacitor 10 . The cutting line Lx is parallel to the X-axis, and the cutting line Ly is parallel to the Y-axis.

As shown in FIG. 5, unfired first internal electrodes 112 corresponding to the first internal electrodes 12 are formed on the first ceramic sheet 101 , and unfired first internal electrodes 112 corresponding to the second internal electrodes 13 are formed on the second ceramic sheet 102 . A sintered second internal electrode 113 is formed. No internal electrodes are formed on the third ceramic sheet 103 corresponding to the cover portion 20 .

The internal electrodes 112, 113 can be formed by applying any conductive paste to the ceramic sheets 101, 102. FIG. A method for applying the conductive paste can be arbitrarily selected from known techniques. For example, a screen printing method or a gravure printing method can be used to apply the conductive paste.

In the first ceramic sheet 101, a strip-shaped non-electrode-forming region N1, to which the internal electrode 112 is not applied, is formed along the cutting line Ly. Similarly, in the second ceramic sheet 102, a strip-shaped non-electrode-forming region N2 where the internal electrode 113 is not applied is formed along the cutting line Ly. The non-electrode formation regions N1 and the non-electrode formation regions N2 are alternately arranged in the X-axis direction. That is, the cutting lines Ly passing through the non-electrode forming regions N1 and the cutting lines Ly passing through the non-electrode forming regions N2 are arranged alternately.

These ceramic sheets 101, 102 and 103 are laminated as shown in FIG. That is, the first ceramic sheets 101 and the second ceramic sheets 102 are alternately laminated, and the third ceramic sheet 103 is laminated on the top and bottom surfaces of the laminated body of the ceramic sheets 101 and 102 in the Z-axis direction. In the laminated sheet 104, the internal electrode 113 is laminated on the non-electrode forming region N1, and the internal electrode 112 is laminated on the non-electrode forming region N2. Although three third ceramic sheets 103 are laminated in the example shown in FIG. 6, the number of third ceramic sheets 103 can be changed as appropriate.

(Step S02: Crimping)
In step S02, the laminated sheet 104 is crimped from the Z-axis direction.

FIG. 7 is a schematic cross-sectional view seen from the Y-axis direction for explaining the crimping process of step S02.
In the crimping step of this step, a pair of pressure plates S1 are opposed to sandwich the laminated sheet 104 in the Z-axis direction, and the laminated sheet 104 is crimped by pressing these pressure plates S1 toward the laminated sheet 104. . The pressure plate S1 is pressurized by, for example, hydrostatic pressurization or uniaxial pressurization.

Further, an elastic sheet S2 is arranged between the pressure plate S1 and the laminated sheet 104. As shown in FIG. The elastic sheet S2 is composed of a sheet-like elastic body, and is made of polyethylene terephthalate (PET) resin, for example. The elastic sheet S2 is pressed toward the laminated sheet 104 by the pressing plate S1.

Here, in the laminated sheet 104, the capacitance forming region 105 in which both the internal electrodes 112 and 113 are laminated, the first lead region 106a in which the first internal electrode 112 and the non-electrode forming region N2 are laminated, A second lead region 106b in which the internal electrode 113 and the non-electrode formation region N1 are stacked is formed. The capacitance forming region 105 corresponds to the capacitance forming portion 18 and the first cover region 21 of the cover portion 20 . The first drawer region 106 a corresponds to the first drawer portion 19 a and the first cover region 21 of the cover portion 20 . The second drawer region 106 b corresponds to the second drawer portion 19 b and the second cover region 22 of the cover portion 20 . The first and second drawer areas 106 a , 106 b are also collectively referred to as the drawer area 106 .

By pressurizing the laminated sheet 104 with the elastic sheet S2 interposed therebetween, it is possible to form the pull-out area 106 which is recessed inward in the Z-axis direction, as described below.

In the capacitance forming region 105, the ceramic sheets 101, 102, 103 are laminated without gaps, including both the internal electrodes 112, 113. FIG. As a result, the capacitance forming region 105 is stretched in the XY plane by the compression bonding process and compressed substantially uniformly. As a result, a substantially flat surface is formed on the capacitance forming region 105. FIG.

On the other hand, gaps corresponding to the non-electrode formation areas N1 and N2 are formed in the extraction area 106 before pressurization. In addition, the green sheets are softer and easier to stretch than the internal electrodes 112 and 113 . Therefore, the green sheet extended from the capacitance forming region 105 enters the gap due to the pressurization.

Furthermore, the elastic sheet S2 can apply a sufficient load even to the thin drawer area 106 by elastic deformation. As a result, in the lead-out region 106, the green sheets extended from the capacitance forming region 105 and the green sheets that have been laminated before pressing are crimped in the Z-axis direction while extending in the XY plane. Therefore, in the extraction region 106, the thickness between the internal electrodes 12 and 13 gradually decreases from the capacitance forming region 105 side toward the cutting line Ly. As a result, the lead area 106 is formed such that the entire area including the internal electrodes 112 and 113 sinks greatly inward in the Z-axis direction near the cutting line Ly.

(Step S03: Disconnect)
In step S03, the unfired laminated chip 116 shown in FIG. 8 is produced by cutting the laminated sheet 104 pressure-bonded in step S02 along the cutting lines Lx and Ly. The laminated chip 116 corresponds to the laminated portion 16 after firing. For cutting the crimped laminated sheet 104, for example, a press cutting blade or a rotating blade can be used.

As shown in FIG. 8, the laminated chip 116 includes an unfired capacitor forming portion 118 corresponding to the capacitor forming portion 18, an unfired lead portion 119 corresponding to the lead portion 19, and an unfired lead portion 119 corresponding to the cover portion 20. and a cover portion 120 of In the capacitance forming portion 118, both internal electrodes 112 and 113 are alternately laminated between green sheets corresponding to ceramic layers. On the other hand, the lead portion 119 is laminated with either one of the internal electrodes 112 and 113 sandwiching a green sheet.

The laminated chip 116 has two end faces 116a facing each other in the X-axis direction, two side faces 116b facing each other in the Y-axis direction, and two principal faces 116c facing each other in the Z-axis direction. , are formed.
The end surface 116a and the side surface 116b correspond to the cut surfaces in the cutting process and are configured as substantially flat surfaces.

The main surface 116c is formed by pressing the outermost third ceramic sheet 103 constituting the unfired cover portion 120 from the Z-axis direction in the pressure bonding step of step S02. A flat region 116d corresponding to the capacitance forming region 105 is formed on the main surface 116c.

Further, on the outer side of the flat region 116d of the principal surface 116c, a curved surface that curves inward in the Z-axis direction is formed corresponding to the drawn-out region 106 formed in the crimping step of step S02. Therefore, the side surface 116b of the laminated chip 116 has rounded corners 116g resulting from the curved surface, and is configured in a rectangular shape with rounded corners.

(Step S04: Side Margin Formation)
In step S04, an unfired side margin portion 117 is provided on the side surface 116b of the laminated chip 116 obtained in step S03 where the internal electrodes 112 and 113 are exposed. The step S05 of forming the side margin portions 117 will be described below with reference to FIGS.

First, as shown in FIG. 9, a ceramic sheet 117s is placed on a flat plate-shaped base member S3 made of an elastic body, and the other side 116b of the laminated chip 116, which is held by tape T on one side 116b, is attached to the ceramic sheet. 117s.

Next, as shown in FIG. 10, the side surface 116b of the laminated chip 116 presses the ceramic sheet 117s in the Y-axis direction. The laminated chip 116 locally sinks deeply into the base member S3 together with the ceramic sheet 117s. At this time, a shear force acts on the ceramic sheet 117s along the outer edge of the side surface 116b, and when this shear force exceeds the shear strength of the ceramic sheet 117s, the ceramic sheet 117s is punched out. As a result, as shown in FIG. 11, the portion of the ceramic sheet 117s sunken together with the laminated chip 116 is cut off as a side margin portion 117. As shown in FIG.

FIG. 12 shows an unfired ceramic body 111 in which an unfired side margin portion 117 is formed on a laminated chip 116. As shown in FIG. The side margin portion 117 is provided only on the side surface 116b and has a planar shape corresponding to the shape of the side surface 116b.

(Step S05: Firing)
In step S05, the ceramic body 11 of the multilayer ceramic capacitor 10 shown in FIGS. 1 to 3 is produced by firing the unfired ceramic body 111 obtained in step S04. The sintering temperature in step S<b>05 can be determined based on the sintering temperature of the ceramic body 111 . Also, the firing can be performed, for example, in a reducing atmosphere or in a low oxygen partial pressure atmosphere.

(Step S06: External electrode formation)
In step S06, external electrodes 14 and 15 are formed on both ends of the ceramic body 11 obtained in step S05 in the X-axis direction. A method for forming the external electrodes 14 and 15 in step S06 can be arbitrarily selected from known methods. Thereby, the laminated ceramic capacitor 10 as shown in FIGS. 1 to 3 is formed.

Part of the processing in step S06 may be performed before step S05. For example, before step S05, an unfired electrode material is applied to both end surfaces of the unfired ceramic body 111 in the X-axis direction, and in step S05, the unfired ceramic body 111 is fired and the unfired electrodes are coated. The material may be baked to form the underlying layers of the external electrodes 14 and 15 . Alternatively, an unfired electrode material may be applied to the ceramic body 111 from which the binder has been removed, and these may be fired at the same time.

By the above, the multilayer ceramic capacitor 10 is completed. In this manufacturing method, since the side margin portion 17 is attached later to the side surface 16b of the laminated portion 16 where the internal electrodes 12 and 13 are exposed, the Y-axis direction of the end portions of the plurality of internal electrodes 12 and 13 in the ceramic element body 11 is increased. The positions are aligned along the Z-axis with a variation of within 0.5 μm.

Further, a corner portion 163 is formed on the side surface 16b of the stacked portion 16 after firing so as to correspond to the rounded corner portion 116g formed on the side surface 116b of the unfired stacked chip 116 . The shape of the side surface 16b will be described below.

[Detailed Configuration of Side 16b of Laminated Part 16]
FIG. 13 is a partial cross-sectional view showing the laminated portion 16 of FIG.

The side surface 16b is configured in a substantially rectangular shape with rounded corners when viewed from above in the Y-axis direction. That is, the side surface 16b includes two first linear portions 161 formed by the outer edges of the two main surfaces 16c, two second linear portions 162 formed by the outer edges of the two end surfaces 16a, and the first linear portion and four curved corners 163 connecting between 161 and the second straight portion 162 . The two first straight portions 161 face each other in the Z-axis direction, and the two second straight portions 162 face each other in the X-axis direction.

The side surface 16b is substantially symmetrical with respect to the Z-axis direction and the X-axis direction. Therefore, the configuration of one corner portion 163 and the first straight portion 161 and the second straight portion 162 connected thereto will be described in detail below.

The first linear portion 161 is a linear portion extending in the X-axis direction and is configured by the flat region 16d of the main surface 16c. That is, the first linear portion 161 corresponds to the flat region 116d formed by the pressure bonding process in step S02 and is formed on the first cover region 21 covering the capacitance forming portion 18. FIG.
Note that the first straight portion 161 may be substantially straight, and meanders or curves in the Z-axis direction within a small range of, for example, 1% or less of the height dimension of the ceramic body 11 in the Z-axis direction. may

The end point P1 of the first linear portion 161 is positioned at the X-axis direction peripheral portion of the first cover area 21 . Here, in the pressure bonding process of step S02, a load concentrates on the capacitance forming region 105, and the ceramic sheets 101, 102, 103 are extended from the capacitance forming region 105 toward the extraction region . As a result, the compression rate may be higher in the X-axis direction peripheral portion of the capacitance forming region 105 than in the central portion. Therefore, in the X-axis direction, the end point P1 is the same as the boundary portion of the lead portion 19 with the capacitance forming portion 18 (that is, the end portion P3 described later), or is closer to the capacitance forming portion 18 than the end P3 of the lead portion 19 is. will be located.

The second linear portion 162 extends in the Z-axis direction and is formed by the outer edge of the flat end face 16a. As a result, the end point P2 of the second linear portion 162 is positioned at the end of the end face 16a in the Z-axis direction.
In addition, the second straight portion 162 may be substantially straight. For example, the second straight portion 162 may meander or bend in the X-axis direction within a small range of 0.5% or less of the length dimension of the ceramic body 11 in the X-axis direction. You may have

The corner portion 163 is a curved portion connecting the end point P1 of the first straight portion 161 and the end point P2 of the second straight portion 162, and corresponds to the corner portion 116g of the unfired side surface 116b as described above. The corner portion 163 is formed by the Y-axis direction outer edge of the X-axis direction peripheral portion of the main surface 116 c and is mainly formed by the second cover region 22 that covers the lead portion 19 .

The shape of corner 163 is defined by the following ratios and values of a and b. a is a value corresponding to the height dimension of the corner portion 163 along the Z-axis direction, and b is a value corresponding to the length dimension of the corner portion 163 along the X-axis direction. This defines the preferred shape of corner 163 .

More specifically, a is along the Z-axis direction between the first virtual line L1 extending from the first straight portion 161 and the end point P2 of the second straight portion 162 on the first virtual line L1 side. distance. The value of a increases as the compressibility of the drawn-out region 106 formed in the crimping step of step S02 increases. Thereby, the value of a can be adjusted by at least one of the number of lamination of the ceramic sheets 101 and 102 and the thickness of the ceramic sheets 101 and 102 .

b is a second virtual line L2 along which the second linear portion 162 is extended; and the distance along the X-axis direction. The value of b can be adjusted by adjusting the dimension of the lead portion 19 in the X-axis direction.

Actually, since it is difficult to control the position of the end point P1 of the first linear portion 161 in the X-axis direction, the length dimension along the X-axis direction of the corner portion 163 from the end point P1 to the second imaginary line L2 and b values may not match. However, the second cover area 22 on the lead-out portion 19 is certainly curved inward in the Z-axis direction to form the corner portion 163 . Therefore, in this embodiment, in order to define the length dimension of the corner portion 163 in the X-axis direction, b corresponding to the length dimension in the X-axis direction of the outermost layer in the Z-axis direction of the lead portion 19 is used. .

The corner portion 163 is curved so as to satisfy the conditions of 0.4≦a/b≦2.5 and 10 μm≦a, b≦60 μm. As a result, in step S04, the ceramic sheet 117s can be punched well, and the side margin portion 117 having an appropriate shape can be provided only on the side surface 16b.
The effects of the corner portion 163 will be described below using a comparative example.

FIG. 14 is a perspective view showing an unfired laminated chip 216 according to a comparative example of this embodiment.
As with the laminated chip 116, the laminated chip 216 includes an unfired capacitance forming portion 218 in which the internal electrodes 212 and 213 are laminated, two lead portions 219 in which one of the internal electrodes 212 and 213 is led out, and an unfired capacitor forming portion 218. and a firing cover portion 220 . Like the laminated chip 116, the laminated chip 216 has two end faces 216a facing each other in the X-axis direction, two side faces 216b facing each other in the Y-axis direction, and two end faces 216b facing each other in the Z-axis direction. Two major surfaces 216c are formed.

The laminated chip 216 is configured such that the entire main surface 216c is substantially flat. Therefore, the corner 216g of the side surface 216b is formed to be more angular than the corner 116g. That is, the corner portion 216g of the side surface 216b after firing satisfies at least one of 0.4>a/b and 10 μm>a, and 0.4≦a/b≦2.5 and 10 μm≦ The condition of a, b≦60 μm is not satisfied.

Such a laminated chip 216 is formed, for example, by printing a ceramic paste on the non-electrode forming regions N1 and N2 of the ceramic sheets 101 and 102. As shown in FIG. As a result, the thickness in the Z-axis direction of the ceramic sheets 101 and 102 becomes uniform within the plane, and the thickness in the Z-axis direction also becomes substantially uniform in the laminated sheet in which these are laminated. Therefore, even in the crimping step of step S02, the lead-out region is hardly curved, and the laminated chip 216 having an angular shape is manufactured.

In the step of forming the side margin portion 217 in the laminated chip 216, first, the side surface 216b of the laminated chip 216 is made to face the ceramic sheet 117s, similarly to the laminated chip 116 in FIG. 10, the side surface 216b of the laminated chip 216 presses the ceramic sheet 117s.

FIG. 15 is a schematic plan view seen from the Y-axis direction, showing a mode in which the side surface 216b of the laminated chip 216 presses the ceramic sheet 117s. 15, illustration of the tape T and the internal electrodes 112 and 113 shown in FIGS. 9 to 11 is omitted.

The corners 216g of the side surfaces 216b are angular as described above. Therefore, in the vicinity of the corner 216g of the ceramic sheet 117s, both the shearing force acting by the outer edge of the substantially flat principal surface 216c and the shearing force acting by the substantially flat end surface 216a are applied. That is, the shearing force along the Z-axis direction and the shearing force along the X-axis direction are concentrated in the vicinity of the corner 216g of the ceramic sheet 117s. As a result, a strong shear stress is generated near the corner 216g of the ceramic sheet 117s, and a crack R is generated in the ceramic sheet 117s.

Therefore, as shown in FIG. 16, when the ceramic sheet 117s is punched at the side surface 216b, the ceramic sheet 117s is broken due to the crack R, and the side margin portion 217 with the fragment F attached thereto is formed.

As a result, as shown in FIG. 17, an unfired ceramic body 211 is formed in which the fragments F extending from the side margin portions 217 are attached to the end face 216a and the principal face 216c other than the side face 216b. Fragments F make the appearance of the multilayer ceramic capacitor poor and reduce the yield.

Therefore, in the multilayer ceramic capacitor 10, the non-fired corners 116g are formed to be greatly curved so that the corners 163 of the fired side faces 16b satisfy the conditions of 0.4≦a/b and 10 μm≦a. . Therefore, in the process of forming the side margin portions 117 in step S04, a shearing force along the outer edges of the corner portions 116g can be applied to the ceramic sheet 117s. As a result, the load applied to the ceramic sheet 117s can be dispersed, and breakage of the ceramic sheet 117s can be prevented. Therefore, the ceramic sheet 117s can be punched out in a shape along the outer edge of the side surface 116b, and the appearance defect of the multilayer ceramic capacitor 10 can be prevented.

On the other hand, when the corners of the side surfaces of the laminated portion satisfy a, b>60 μm, the ratio of the corners occupying the side surfaces increases, and the corners are further curved. In this case, in the step of forming the side margins, the shearing force applied to the ceramic sheet by the side surface is reduced, making it difficult to punch out the ceramic sheet.

Similarly, when a/b>2.5 at the corners, the corners are greatly curved inward in the Z-axis direction, which may result in defective punching of the ceramic sheet. Furthermore, in this case, the vicinity of the end point of the first linear portion may have an angular shape. As a result, the shearing force concentrates on the ceramic sheet near the end point of the first linear portion, and the appearance defect similar to that of the ceramic body 211 in FIG. 17 may occur.

Therefore, in the multilayer ceramic capacitor 10, the corners 163 of the side surfaces 16b after firing satisfy the conditions of a/b≦2.5 and a, b≦60 μm, so that the unfired side surfaces 116b are formed into ceramic sheets 117s. can exert a sufficient shear force on the Therefore, it is possible to prevent defective punching of the ceramic sheet 117s.

In addition, by satisfying the condition that the corner 163 of the side surface 16b after firing satisfies the condition of 10 μm≦b, the length dimension along the X-axis direction of the lead-out portion 19 is sufficiently secured, and the withstand voltage at the end margin is sufficiently secured. can do. Furthermore, it is possible to suppress electrical conduction between the first external electrode 14 and the second internal electrode 13 and between the second external electrode 15 and the first internal electrode 12 due to misalignment of the ceramic sheets 101 and 102 in the laminated sheet 104 . Therefore, it is possible to prevent a short circuit from occurring in the lead portion 19 .

In summary, the multilayer ceramic capacitor 10 is produced so that the corner 163 of the side surface 16b satisfies the conditions of 0.4≦a/b≦2.5 and 10 μm≦a, b≦60 μm. It is possible to form the shaped side margin portion 17 and sufficiently secure the reliability of the multilayer ceramic capacitor 10 . Thereby, the yield of the laminated ceramic capacitor 10 can be increased.

Furthermore, by satisfying the condition of 0.5≦a/b≦1.5, the corner portion 163 can more reliably prevent appearance defects and further increase the yield of the multilayer ceramic capacitor 10 .

Further, in order to increase the capacitance of the multilayer ceramic capacitor 10 without changing the size of the ceramic element body 11, the crossing area of the internal electrodes 12 and 13 is increased and the length dimension of the lead portion 19 along the X-axis direction is increased. should be shortened. For example, the corner 163 can be designed so as to satisfy the condition of 10 μm≦b≦30 μm in consideration of the insulating properties of the end margin.

In this case, by satisfying the condition of 1.0≦a/b≦1.5 for the corner portion 163, even if the corner portion 163 is small, an appropriate shearing force can be applied to the ceramic sheet 117s. As a result, it is possible to realize a laminated ceramic capacitor 10 that is small in size and has a large capacity and is provided with the side margin portions 17 of an appropriate shape.

[Examples and Comparative Examples]
As examples of the present embodiment and comparative examples, samples of multilayer ceramic capacitors having side surfaces of multilayer portions of various shapes were produced, and occurrence of defects during formation of side margin portions was investigated. These samples had an X-axis dimension of 1.0 mm and a Y-axis and Z-axis dimension of 0.5 mm.

Table 1 shows the values of a and b at the corners of the side surfaces measured in the samples of each example and comparative example of the multilayer ceramic capacitor, and the values of a/b calculated from these values. The values shown in Table 1 are all average values of 100 samples in each example and comparative example.

a is a value corresponding to the height dimension along the Z-axis direction of the corner. That is, as shown in FIG. 13, a is a first imaginary line (L1) extending from a first straight portion (161) along the X-axis direction of the side surface (16b) and a The distance along the Z-axis direction between the end point (P2) of the second straight portion (162) on the side of the first imaginary line (L1) along the Z-axis direction.

b is a value corresponding to the length dimension along the X-axis direction of the corner. That is, as shown in FIG. 13, b is the second imaginary line (L2) to which the second linear portion (162) is extended, and the end portion of the lead portion (19), which is the capacitance forming portion (18). The distance along the X-axis direction between the end portion (P3) located at the boundary with the cover portion (20).

As shown in Table 1, the corners of the samples of Examples 1 to 11 all satisfied the conditions of 0.4≦a/b≦2.5 and 10 μm≦a, b≦60 μm.

On the other hand, the samples of Comparative Examples 1 and 2 each had a of 9 μm, which did not satisfy the condition of 10 μm≦a.
Furthermore, the sample of Comparative Example 1 had a/b of 0.24, which did not satisfy the condition of 0.4≦a/b.
The sample of Comparative Example 3 had a of 61 μm and b of 62 μm, and did not satisfy the condition of a≦60 μm.
The sample of Comparative Example 4 had a of 61 μm and a/b of 2.90, and did not satisfy the conditions of a≦60 μm and a/b≦2.5.

Regarding the samples of Examples 1 to 11 and Comparative Examples 1 to 4, the number of occurrences of defective punching of the ceramic sheets for forming the side margin portions was examined. The punching failure in this case means that the ceramic sheet cannot be punched out in whole or in part when forming the side margins, and the side margins cannot be formed on the side surfaces.

In Examples 1 to 11 in which the corners satisfies the conditions of 0.4≦a/b≦2.5 and 10 μm≦a, b≦60 μm, no punching defects occurred.

On the other hand, in Comparative Example 3, in which both the values of a and b were larger than 60 μm, a very large number of defective punching occurred in 30 out of 100 samples. For this reason, even if the corner satisfies the condition of 0.4≦a/b≦2.5, if the condition of a, b≦60 μm is not satisfied, punching failure occurs, and the side margin portion is not properly formed. It was confirmed that it is difficult to set

Furthermore, in Comparative Example 4 in which a/b is greater than 2.5, punching defects occurred in 5 out of 100 samples. As a result, it was confirmed that when a/b is greater than 2.5 at the corners, the shearing force exerted on the ceramic sheet becomes unstable, making it difficult to appropriately provide the side margins.

Next, among the samples of Examples 1 to 11 and Comparative Examples 1 to 4, the appearance of the samples for which no punching failure occurred was caused by the fragments of the ceramic sheets for forming the side margins adhering to areas other than the side surfaces of the laminate. The number of defects was investigated. Specifically, 100 samples of Examples 1 to 11 and Comparative Examples 1 and 2, 70 samples of Comparative Example 3, and 95 samples of Comparative Example 4 were examined for the number of appearance defects.

In Comparative Examples 1 and 2 in which the value of a was less than 10 μm, 9 or 10 out of 100 samples had poor appearance. Also in Comparative Example 4 in which the value of a is greater than 60 μm and the value of a/b is greater than 2.5, out of the 95 samples in which no punching defects occurred, 9 had appearance defects.

On the other hand, in Examples 1 to 11, out of 100 samples, the number of samples with poor appearance was 2 or less, and the yield was good. For example, even in Example 9 in which the value of a/b is 0.40 and Example 1 in which the value of a/b is 2.26, only two samples had poor appearance. Of the 70 samples in Comparative Example 3 in which no punching defects occurred, none of the samples had appearance defects.

Therefore, by satisfying the conditions of 10 μm≦a and 0.4≦a/b≦2.5 for the corner portion, it is possible to suppress occurrence of poor appearance due to wraparound of the ceramic sheet for forming the side margin portion. was confirmed.

In fact, when the shapes of the side surfaces of the samples of Examples 1 to 11 were compared with the side surfaces of the samples of Comparative Examples 1, 2, and 4 in which appearance defects occurred, the corners of Examples 1 to 11 were more rounded. The corners of Comparative Examples 1, 2 and 4 were more angular. From this, it is considered that the concentration of the shearing force in the vicinity of the corners of the ceramic sheet can be suppressed by satisfying the condition of 0.4≦a/b≦2.5 for the corners.

Furthermore, in Examples 3 to 7 in which the a/b value of the corner portion is 0.52 (Example 7) or more and 1.45 (Example 3) or less, the above-described appearance defects did not occur in all 100 samples. rice field. Accordingly, it was confirmed that by satisfying the condition of 0.5≦a/b≦1.5 for the corner portion, it is possible to more reliably prevent appearance defects.

In addition, among Examples 3 to 7 in which no appearance defects occurred, in Example 3 in which the value of b was 29 μm, the value of a/b was 1.45, and in Example 4 in which the value of b was 28 μm. , the value of a/b was 1.07. As a result, even when the length dimension of the lead-out portion is reduced so as to satisfy 10 μm≦b≦30 μm, by designing the corner so as to satisfy 1.0≦a/b≦1.5, the poor appearance can be prevented. It was confirmed that this could be prevented. That is, by satisfying 10 .mu.m.ltoreq.b.ltoreq.30 .mu.m and 1.0.ltoreq.a/b.ltoreq.1.5 for the corner portion, it is possible to increase the yield and widen the intersecting area of the internal electrodes to increase the capacity.

In addition, in multilayer ceramic capacitors with lead-out portions (end margins) of less than 10 μm, short circuits due to lamination misalignment and insufficient dielectric strength may occur, and sufficient reliability as multilayer ceramic capacitors is ensured. I couldn't. Therefore, it was confirmed that the reliability of the multilayer ceramic capacitor can be ensured by setting b corresponding to the length dimension of the lead portion to 10 μm or more.

As described above, by satisfying the conditions of 0.4 ≤ a/b ≤ 2.5 and 10 μm ≤ a, b ≤ 60 μm for the corners, the occurrence of defects such as poor punching and poor appearance when forming the side margins is suppressed. confirmed to be possible.

Although each embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

The manufacturing method of the laminated ceramic capacitor 10 is not limited to the manufacturing method described above as long as the corner portions 163 having the above-described shape can be formed on the side surfaces 16b of the laminated portion 16 .

Furthermore, in the multilayer ceramic capacitor 10, the capacitance forming portion 18 may be divided into a plurality of portions in the Z-axis direction. In this case, it is sufficient that the internal electrodes 12 and 13 are alternately arranged along the Z-axis direction in each capacitance forming portion 18, and the first internal electrode 12 or the second internal electrode 13 is arranged at the portion where the capacitance forming portion 18 is switched. They may be arranged continuously.

Reference Signs List 10 Laminated ceramic capacitor 11 Ceramic element body 12, 13 Internal electrodes 14, 15 External electrode 16 Laminated portion 17 Side margin portion 18 Capacitance forming portions 19, 19a, 19b Lead portion 20 Cover portion 16a End surface 16b Side surface 16c Main surface 161 First linear portion 162 Second linear portion 163 Corner portion

Claims (1)

a capacitor forming portion in which internal electrodes are stacked in a first direction; a lead portion extending from the capacitor forming portion in a second direction orthogonal to the first direction and from which the internal electrodes are led; a main surface facing the first direction, an end surface facing the second direction, and a third direction perpendicular to the first and second directions. fabricating a laminated chip formed with a side surface facing a direction;
forming a side margin portion on the side surface by punching a ceramic sheet on the side surface;
By firing the laminated chip in which the side margin portion is formed,
A first linear portion extending in the second direction and configured by the outer edge of the main surface; a second linear portion extending in the first direction and configured by the outer edge of the end surface; Forming the side surface after firing having a corner portion connecting the straight portion,
The corner is
the distance along the first direction between the first imaginary line along which the first straight portion extends in the second direction and the end point of the second straight portion on the first imaginary line side; a second imaginary line extending in the first direction from the second linear portion; and an end portion of the lead portion exposed from the side surface and positioned at a boundary between the capacitance forming portion and the cover portion. and b is the distance along the second direction, the laminated ceramic is curved so as to satisfy the conditions of 0.4≦a/b≦2.5 and 10 μm≦a and b≦60 μm. A method of manufacturing a capacitor.

Images